Dir: Jaume Collet-Serra
I'm terrible at maths, but here's an equation for you. The Fugitive - Harrison Ford + the Bourne franchise - Matt Damon + slumming German actors + January Jones + rentahack = uninspiring Liam Neeson vehicle.
The premise of Unknown isn't uninteresting; Liam Neeson plays Martin Harris, a scientist who goes to Berlin to give a speech but he's involved in a car crash (while in a cab driven by Diane Kruger). He wakes four days later and, on going to find his wife Elizabeth (Jones), discovers that another man (Aidan Quinn) is saying that he's Martin Harris, and is married to Elizabeth, who now says that she's never met Neeson's Martin. With the help of the cab driver, 'Martin' must now find out who he is, and who is trying to be him.
Unknown isn't awful, it's just unremarkable; a slightly undercooked stew of ingredients that were better when served separately. Neeson's performance is energetic, he runs around Berlin trying to put the clues together, and biffs people fairly convincingly in the last 15 minutes of the film (which is, Taken fans be warned, light on action until then), but I'd be lying if I said he was terribly good. It's a workmanlike turn, rather like watching a slightly bored bricklayer make a nice sturdy wall; you can't fault it, but it's tough to be excited by it.
The focus is almost entirely on Neeson, so the other characters are undeveloped ciphers that give the talented supporting cast little to do. Diane Kruger is a good actress (and she can be great, see Anything For Her) but her character has little to do but be imperiled by her association with Neeson, the last thing she does that is of any real use is pull Neeson from a sinking car (how plausible, the 5' 3" Kruger rescuing the soaking wet, unconscious, 6' 5" Neeson) and that happens before she's spoken a single word. January Jones is flat as Neeson's 'wife' and Aidan Quinn gets too little screentime to be threatening as the man who replaces Martin (nice to see you though Aidan). The real shame is the wasting of talented German performers like Bruno Ganz and Sebastien Koch in roles that give them little to do but exposit.
The film is unevenly paced, and director Jaume Collet-Serra lacks the chops to inject real intrigue or excitement into it. The car chases don't really get the pulse racing, and the action is toned down in deference to the 12A certificate. The big twist is mildly surprising, but others are telegraphed well in advance. The real downfall is that neither the script nor the direction (nor indeed the performances) put enough flesh on the bones of these characters to make Neeson's quest feel all that important (and if anything the twist undermines any sympathy you might otherwise have).
Like I said, this isn't terrible, but it's not good either. You're better off watching The Fugitive or the Bourne films really.